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Alkylation of acetylene by tert-butyl alcohol
A reaction of acetylene with tert-butyl alcohol in the presence of sulfuric acid leads to tert-butylacetylene.
Kazakov,Demina
p. 2134 - 2135
(2002)
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Bifunctional Catalysts Based on Tungsten Hydrides Supported on Silicated Alumina for the Direct Production of 2,3-Dimethylbutenes and Neohexene from Isobutene
Well-defined bifunctional supported catalysts that comprise tungsten hydride moieties and Br?nsted acid sites were prepared successfully. The catalysts showed outstanding activities and selectivities toward the formation of high-value-added products, 2,3-dimethylbutenes and 3,3-dimethylbutene, through a combination of the metathesis and dimerization of isobutene. The relationship between the physicochemical properties of the catalysts and their activities and selectivities indicated that isobutene conversion increased from 4 to 95 % as a function of the silica content of the silicated alumina (obtained from Sasol). Nevertheless, the selectivity toward branched hexenes showed a volcano-shaped curve that presented a maximum for the catalyst with 5 wt % silica. Therefore, the control of the support acidity by the silica loading on alumina resulted in an increase of the selectivity toward neohexene.
Larabi, Cherif,Garron, Anthony,Rouge, Pascal,Szeto, Kai C.,Norsic, Sébastien,De Mallmann, Aimery,Merle, Nicolas,Taoufik, Mostafa
p. 2160 - 2166
(2017)
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HYDROTHERMAL PRODUCTION OF ALKANES
Synthesizing an alkane includes heating a mixture including an alkene and water at or above the water vapor saturation pressure in the presence of a catalyst and one or both of hydrogen and a reductant, thereby hydrogenating the alkene to yield an alkane and water, and separating the alkane from the water to yield the alkane. The reductant includes a first metal and the catalyst includes a second metal.
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Paragraph 0022

(2021/04/17)

PROCESS AND CATALYSTS FOR THE PRODUCTION OF DIESEL AND GASOLINE ADDITIVES FROM GLYCEROL
A method of producing one or more glycerol ethers, the method comprising contacting glycerol and tertiary butanol (TBA) in the presence of an acidic catalyst to produce one or more glycerol ethers selected from mono-tert butyl glycerol ethers, di-tert butyl glycerol ethers, tri-tert butyl glycerol ethers, or a combination thereof; separating water and a stream comprising isobutylene, unreacted TBA, or a combination thereof from the one or more glycerol ethers; and recycling at least a portion of the stream comprising isobutylene, unreacted TBA, or a combination thereof to the contacting. Also disclosed is a process of co-producing isooctene, wherein the process involves contacting glycerol and tertiary butanol in the presence of a dehydrating catalyst and dimerizing/oligomerizing the dehydrated products in the presence of an oligomerizing catalyst to form isooctene, a precursor of isooctane and isomers thereof.
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Paragraph 0043-0045

(2020/01/24)

Identification of the strong Br?nsted acid site in a metal–organic framework solid acid catalyst
It remains difficult to understand the surface of solid acid catalysts at the molecular level, despite their importance for industrial catalytic applications. A sulfated zirconium-based metal–organic framework, MOF-808-SO4, was previously shown to be a strong solid Br?nsted acid material. In this report, we probe the origin of its acidity through an array of spectroscopic, crystallographic and computational characterization techniques. The strongest Br?nsted acid site is shown to consist of a specific arrangement of adsorbed water and sulfate moieties on the zirconium clusters. When a water molecule adsorbs to one zirconium atom, it participates in a hydrogen bond with a sulfate moiety that is chelated to a neighbouring zirconium atom; this motif, in turn, results in the presence of a strongly acidic proton. On dehydration, the material loses its acidity. The hydrated sulfated MOF exhibits a good catalytic performance for the dimerization of isobutene (2-methyl-1-propene), and achieves a 100% selectivity for C8 products with a good conversion efficiency.
Trickett, Christopher A.,Osborn Popp, Thomas M.,Su, Ji,Yan, Chang,Weisberg, Jonathan,Huq, Ashfia,Urban, Philipp,Jiang, Juncong,Kalmutzki, Markus J.,Liu, Qingni,Baek, Jayeon,Head-Gordon, Martin P.,Somorjai, Gabor A.,Reimer, Jeffrey A.,Yaghi, Omar M.
p. 170 - 176
(2018/11/27)

Olefin oligomerization via new and efficient Br?nsted acidic ionic liquid catalyst systems
Olefin oligomerization reaction catalyzed by new catalyst systems (a Br?nsted-acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co-catalyst) has been investigated. The synthesized Br?nsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV), 1H nuclear magnetic resonance (NMR), and 13C NMR to analyze their structures and acidities. The influence of different ionic liquids, ionic liquid loading, different co-catalysts, catalyst ratios (mole ratio of ionic liquid to co-catalyst), reaction time, pressure, temperature, solvent, source of reactants, and the recycling of catalyst systems was studied. Among the synthesized ionic liquids, 1-(4-sulfonic acid)butyl-3-hexylimidazolium hydrogen sulfate ([HIMBs]HSO4) exhibited the best catalytic activity under the tested reaction conditions. The conversion of isobutene and selectivity of trimers were 83.21% and 35.80%, respectively, at the optimum reaction conditions. Furthermore, the catalyst system can be easily separated and reused; a feasible reaction mechanism is proposed on the basis of the distribution of experimental products.
Wang, Guoqin,Song, Heyuan,Li, Ruiyun,Li, Zhen,Chen, Jing
p. 1110 - 1120
(2018/05/28)

The feeding at the same time containing butene dimerization and hydrated method (by machine translation)
The present invention provides a mixed butene by acid catalysts containing hydrocarbon feed of manufacturing and method of the oligomer at the same time. Furthermore, embodiments of the present invention also provides the preparation of the mixed olefin containing the alcohol and the oligomer process for the preparation of the fuel composition, in certain embodiments, the catalyst can include two-phase catalyst system, the catalyst system includes a water-soluble acid catalyst and solid acid catalyst. (by machine translation)
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Paragraph 0071-0077

(2017/03/22)

Fluorinated metal oxide-assisted oligomerization of olefins
Fluorinated alumina is an efficient catalyst for hex-1-ene, cyclohexene and isobutene oligomerization, whereas fluorinated titania and zirconia are inactive.
Lermontov, Sergey A.,Malkova, Alena N.,Yurkova, Lyudmila L.,Ivanov, Vladimir K.,Baranchikov, Alexander E.,Vasilyeva, Larisa P.
p. 110 - 112
(2013/05/21)

Byproducts formation in the ethyl tert-butyl ether (ETBE) synthesis reaction on macroreticular acid ion-exchange resins
Ethyl tert-butyl ether (ETBE) production is one of the industrial processes of major importance today in Europe. However, the study of side reactions in this synthesis reaction appears scarcely in the open literature. Side reactions take place along with the etherification of C4 olefinic cuts with ethanol, catalyzed by acidic ion-exchange resins. In this work, byproducts formation is studied in a batch reactor. The presence of diethyl ether (DEE), ethyl sec-butyl ether (ESBE), dimers of isobutene (2,4,4-trimethyl-1-pentene (TMP-1) and 2,4,4-trimethyl-2-pentene (TMP-2)) and tert-butyl alcohol (TBA) has been studied in terms of production and selectivity. The effect of temperature, ranging from 323 to 383 K, and the influence of initial molar ratio ethanol/isobutene (R A/O), ranging from 0.5 to 2.0, on byproducts formation have been analyzed. All byproducts formation was favored by high temperatures. A low initial molar ratio ethanol/isobutene favored the formation of DEE, ESBE, TMP-1 and TMP-2, whereas high molar ratios favored TBA formation.
Badia,Fité,Bringué,Ramírez,Cunill
p. 384 - 394
(2013/10/22)

Highly efficient trimerization of isobutene over silica supported chloroaluminate ionic liquid using C4 feed
A series of silica, glass and molecular sieves supported chloroaluminate ionic liquids (ILs) were prepared and their catalytic performance on the trimerization of isobutene based on C4 mixture was investigated. Interestingly, it was found that the carrier played a key role in the reaction route. Among these supported catalysts, silica supported chloroaluminate ionic liquid was highly efficient for the trimerization of isobutene. X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC) characterizations suggested that the synergy between Al2Cl7- anion and silica induced the catalytic activity for isobutene oligomerization due to the strong interaction between ILs and silanol group. The reaction conditions including loading amount, temperature, reactant concentration, and space velocity for the isobutene oligomerization were optimized. Ultimately, complete conversion of isobutene and 91.4% selectivity of trimers were obtained over the IL/silica (30 wt.%) catalyst at mild conditions. Moreover, catalyst stability and deactivation were preliminarily studied.
Liu, Shimin,Shang, Jianpeng,Zhang, Shiguo,Yang, Benqun,Deng, Youquan
p. 41 - 48
(2013/02/23)

Sulfated SnO2 as a high-performance catalyst for alkene oligomerization
Nanoparticulate (3-5 nm) sulfated tin dioxide shows high catalytic activity for the oligomerization of isobutylene, hexene-1, and cyclohexene. The acidity (Hammett acidity function H0) of sulfated stannia reaches H 0 = -16.04. We have studied the effect of synthesis conditions on the physicochemical and functional properties of sulfated SnO2.
Yurkova, L. L.,Lermontov, S. A.,Kazachenko, V. P.,Ivanov, V. K.,Lermontov, A. S.,Baranchikov, A. E.,Vasil'Eva, L. P.
p. 1012 - 1019,8
(2012/12/11)

Sulfated SnO2 as a high-performance catalyst for alkene oligomerization
Nanoparticulate (3-5 nm) sulfated tin dioxide shows high catalytic activity for the oligomerization of isobutylene, hexene-1, and cyclohexene. The acidity (Hammett acidity function H0) of sulfated stannia reaches H 0 = -16.04. We have studied the effect of synthesis conditions on the physicochemical and functional properties of sulfated SnO2.
Yurkova,Lermontov,Kazachenko,Ivanov,Lermontov,Baranchikov,Vasil'Eva
p. 1012 - 1019
(2013/01/15)

Etherification of glycerol by isobutylene: Tuning the product composition
Etherification of glycerol by isobutylene was conducted in a batch mode using acidic and partially neutralized Amberlyst-15 ionic resin, p-toluenesulfonic acid, silicotungstic acid, cesium salt of silicotungstic acid, and ionic liquid containing sulfonic acid groups. All the catalysts are comparable in terms of the initial rate of glycerol conversion into mono-ether (except cesium salt of heteropolyacid), but differ substantially with respect to the yields of higher ethers of glycerol. Ionic liquid and heteropolyacid are immiscible/insoluble in higher ethers of glycerol. As a result they have unique capability of suppressing the formation of tri-ether during the initial stage of glycerol conversion. Acidic Amberlyst-15 in the form of fine powder has the highest activity per unit weight for glycerol etherification and relatively high activity in isobutene oligomerization. Partial exchange of acidic protons with cations Na+, Ag+, Mg2+, and Al3+ decreases the rates of all the processes, but isobutylene oligomerization is suppressed more efficiently. Ag+- and Al3+-modified Amberlyst demonstrates higher yields of tri-ether and has specific pattern of interaction with gaseous isobutene distinctive to other metal-substituted Amberlysts.
Lee, Hee Jong,Seung, Doyoung,Jung, Kwang S.,Kim, Hwayong,Filimonov, Igor N.
scheme or table
p. 235 - 244
(2012/01/02)

Selective and unexpected transformations of 2-methylpropane to 2,3-dimethylbutane and 2-methylpropene to 2,3-dimethylbutene catalyzed by an alumina-supported tungsten hydride
2-Methylpropane and 2-methylpropene, in the presence of the W(H) 3/Al2O3 catalyst, are unexpectedly transformed to 2,3-dimethylbutane and 2,3-dimethylbutenes, respectively, with high selectivity; in case of 2-methylpropane
Merle, Nicolas,Stoffelbach, Francois,Taoufik, Mostafa,Le Roux, Erwan,Thivolle-Cazat, Jean,Basset, Jean-Marie
body text
p. 2523 - 2525
(2009/09/30)

OLIGOMERISATION
The application discloses novel processes for the oligomerisation of unsaturated hydrocarbons, and more specifically the use of selected ionic liquids in the oligomerisation of unsaturated hydrocarbons, which allows for selection of the oligomers formed.
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(2008/06/13)

PREPARING METHOD OF LIGHT OLEFIN TRIMERS AND PRODUCTION OF HEAVY ALKYLATES BY USING THEREOF
The present invention relates to a preparation method of olefin oligomers, and more particularly, to a preparation method of olefin trimers with high selectivity. The oligomerization is performed with a catalyst such as a zeolite having cross linking pores; a composite acid catalyst having both Br?nsted acid and Lewis acid; or a composite catalyst post-treated by calcination and/or water-washing. Furthermore, the present invention relates to a preparation method of heavy alkylates by hydrogenating olefin trimers thus formed.
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Page/Page column 18

(2008/06/13)

Diisobutylene process
This invention is a process for producing diisobutylene from isobutylene. The process comprises contacting isobutylene with a solid adsorbent to remove sulfur and/or nitrogen impurities from the isobutylene, followed by oligomerizing the isobutylene to diisobutylene using a sulfonic acid-type ion exchange resin. The solid adsorbent removes sulfur and/or nitrogen impurities from the isobutylene and surprisingly increases both catalyst activity and catalyst life of the sulfonic acid-type ion exchange resin.
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Page/Page column 2-3

(2008/06/13)

Process and apparatus for oligomerization in multiple stages with single fractionation column
In an oligomerization process comprising at least two oligomerization reactors, at least portions of product streams from two reactors are separated in the same separator vessel. In an embodiment, a liquid product stream from the first oligomerization reactor is fed to a fractionation column and a side cut from the fractionation column feeds the second oligomerization reactor.
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Page/Page column 4

(2008/06/13)

COMPOSITE CATALYST FOR THE SELECTIVE OLIGOMERIZATION OF LOWER ALKENES AND THE PRODUCTION OF HIGH OCTANE PRODUCTS
The present invention relates to a) a catalytic composite comprising a support structure and a catalytic species that is deposited on the support structure, b) a process for the selective oligomerization of lower alkenes and mixtures of alkenes, which process comprises contacting the lower alkenes with the catalytic composite in a catalytic distillation apparatus and under catalytic distillation conditions, and c) a process for producing high octane products, which process comprises hydrogenating one or more catalytic distillation apparatus and under catalytic distillation conditions.
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Page/Page column 48-52

(2008/06/13)

Production of diisobutene from tertiary butyl alcohol
A process for the production of diisobutene is disclosed wherein tertiary butyl alcohol is dehydrated to isobutene in a distillation column reactor containing an acid cation exchange resin catalyst in the form of catalytic distillation structure. The isobutene reacts with itself in the presence of the catalyst to form primarily diisobutene which is removed as bottoms from the distillation column reactor with the bulk of the water. Unreacted isobutene along with an azeotrope of water is removed as overheads with the water being separated and removed from the unreacted isobutene. A portion or all of the unreacted isobutene may be returned to the distillation column reactor as reflux.
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(2008/06/13)

Re-based heterogeneous catalysts for olefin metathesis prepared by surface organometallic chemistry: Reactivity and selectivity
Herein we describe the catalytic activity of 1, a well-defined Re alkylidene complex supported silica, in the reaction of olefin metathesis. This system is highly active for terminal and internal olefins with initial rates up to 0.7 mol per mol Re per s. It also catalyses the self-metathesis of methyl oleate (MO) without the need of co-catalysts. The turnover numbers can reach up to 900 for MO, which is unprecedented for a heterogeneous Re-based catalyst. Moreover the use of silica as a support can bring major advantages, such as the possibility to use branched olefins like isobutene, which are usually incompatible with alumina-based supports; therefore, the formation of isoamylene from the cross-metathesis of propene and isobutene can be performed. All these results are in sharp contrast to what has been found for other silica- or alumina-supported rhenium oxide systems, which are either completely inactive (silica system) or typically need co-catalysts when functionalised olefins are used. Finally the initiation step corresponds to a cross-metathesis reaction to give a 3:1 mixture of 3,3-dimethylbutene and trans-4,4-dimethylpent-2-ene, and make this catalyst the first generation of well-defined Re-based heterogeneous catalysts.
Chabanas, Mathieu,Coperet, Christophe,Basset, Jean-Marie
p. 971 - 975
(2007/10/03)

Dilithiated phosphazenes: Scaffolds for the synthesis of olefins through a new class of bicyclic 1,2-oxaphosphetanes
The first examples of the PN-directed dilithiation of (N-methoxycarbonyl)phosphazenes in the Cα and Cortho to the phosphorus, and the use of these dianions in the formation of tri- and tetra-substituted olefins through stereospecific thermolysis of a new type of isolable bicyclic 1,2-oxaphosphetanes are described.
Garcia-Lopez, Jesus,Peralta-Perez, Emma,Forcen-Acebal, Angela,Garcia-Granda, Santiago,Lopez-Ortiz, Fernando
p. 856 - 857
(2007/10/03)

Control of regioselectivity by the lone substituent through steric and electronic effects in the nitrosoarene ene reaction of deuterium-labeled trisubstituted alkenes
For the ene reaction of 4-nitronitrosobenzene (ARNO) with a variety of primary and secondary lone alkyl-substituted substrates, the twix/twin regioselectivity is constant at about 85:15. In contrast, for the lone tert-butyl group and for lone aryl substituents, the twix regioisomer is obtained exclusively. These regioselectivities have been rationalized in terms of steric interactions and coordination between the enophile and the substrates in the transition states of the first reaction step.
Adam, Waldemar,Krebs, Oliver,Orfanopoulos, Michael,Stratakis, Manolis
p. 8395 - 8399
(2007/10/03)

Reactions of aliphatic ketones R2CO (R = Me, Et, iPr, and tBu) with the MCl4/Li(Hg) system (M = U or Ti): Mechanistic analogies between the McMurry, Wittig, and Clemmensen reactions
Analysis of the products of the reactions of ketones R2CO (R = Me, Et, iPr, tBu) with the MCl4/Li(Hg) system (M = U, Ti) at 20°C revealed significant differences. For R = Me, the reaction proceeded exclusively (M = U) or preferentially (M = Ti) via a metallopinacol intermediate resulting from dimerization of ketyl radicals. Pinacol was liberated by hydrolysis, and tetramethylethylene was obtained after further reduction at 65°C. For R = iPr, formation of iPr2C=CiPr2 as the only coupling product, the nonproduction of this alkene by reduction of the uranium pinacolate [U]-OCR2CR2O-[U] (R = iPr) at 20°C, and the instability of the corresponding titanium pinacolate towards rupture of the pinacolic C-C bond indicated that reductive coupling of iPr2CO did not proceed by dimerization of ketyl radicals. Formation of 2,4-dimethyl-2-pentene was in favor of a carbenoid intermediate resulting from deoxygenative reduction of the ketyl. These results revealed that for sterically hindered ketones, McMurry reactions can be viewed as Wittig-like olefination reactions. For R = tBu, no coupling product was obtained and the alkane tBu2CH2 was the major product. The involvement of the carbenoid species [M]=CtBu2 was confirmed by its trapping with H2O, leading to tBu2CH2, and with the aldehydes RCHO, giving the cross-coupling products tBu2C=C(R)H (R = Me, tBu). Therefore, in the case of severely congested ketones, McMurry reactions present strong similarities to the Clemmensen reduction of ketones, owing to the involvement in both reactions of carbenoid species which exhibit similar reactivity. Wiley-VCH Verlag GmbH, 2001.
Villiers, Claude,Ephritikhine, Michel
p. 3043 - 3051
(2007/10/03)

Structural effects on the Grunwald-Winstein correlations in the solvolysis of some simple tertiary alkyl chlorides
The rates of solvolysis in various solvents at 25 °C were determined for five tertiary alkyl chlorides: 2-chloro-2,4,4-trimethylpentane (4), 2-chloro-2,4-dimethylpentane, 2-chloro-2-methylpentane, 1-chloro-1,3,3-trimethyl-cyclopentane (7) and 1-chloro-1-methylcyclopentane. The rate data were analysed on the basis of the original and extended Grunwald-Winstein-type equation [log(k/k0)=myc1+c and log(k/k0)=lNT+mYc1+c] and the results were compared with those reported for 2-chloro-2-methylpropane (1) and 2-chloro-2,3,3-trimethylbutane (3). The rate data for 4 in 18 solvents give an excellent correlation with l=0·00±0·02 and m=0·74±0·01. The neopentyl group in 4 more effectively shields the rear-side of the reaction center than the tert-butyl group in 3 that is correlated by l=0·10±0·04 and m=0·81±0·04. The rate ratio between 4 and 1 at 25 °C is 275 in TFE and predicted to increase to 950 in TFA. The previous 4/1 rate ratio of 21 in 80% ethanol evidently underestimates the B-strain effect on the solvolysis rate of 4 by a factor of at least 40. The remote methyl groups in 7 works to increase rear-side shielding without increasing B-strain. The marked difference in the effect of the remote methyl groups between 4 and 7 suggests that the leaving chloride ion in 4 takes a locus that is nearly antiperiplanar to the tert-butyl group.
Takeuchi, Ken'ichi,Ohga, Yasushi,Ushino, Takuhiro,Takasuka, Masaaki
p. 717 - 724
(2007/10/03)

The Grunwald-Winstein type correlation for 2-chloro-2,4,4- trimethylpentane: A simple tertiary alkyl chloride that shows essentially limiting behaviour in solvolysis
Evaluation of the rates of solvolysis of 2-chloro-2,4,4-trimethylpentane (4) in 17 solvents on the basis of the Grunwald-Winstein type equation [log(k/k0)= lNT+mYC1 + c] gives an excellent correlation with l=-0·01±0·02 and m = 0·74±0·01. The neopentyl group in 4 more effectively shields the rear side of the reaction center than the tert-butyl group in 2-chloro-2,3,3-trimethylbutane. The rate ratio between 4 and 2-chloro-2-methylpropane (3) at 25°C is 275 in trifluoroethanol and predicted to increase to 950 in trifluoroacetic acid. The previous 4:3 rate ratio of 22 in 80% ethanol evidently underestimated the B-strain effect on the solvolysis rate of 4 by a factor of at least 40.
Takeuchi, Ken'Ichi,Ohga, Yasushi,Ushino, Takuhiro,Takasuka, Masaaki
p. 777 - 779
(2007/10/03)

Etudes des reactions d'oxydation du n-heptane et de l'isooctane
The oxidation mechanisms of two alkanes that have quite different octane numbers: n-heptane (0) and isooctane (100), were investigated to obtain a better understanding of the chemical mechanism of autoignition phenomena and to improve the compatibility of the available fuels with the engines.The experimental study was performed at 923 K in a setup equipped with a jet-stirred reactor.The oxidation mechanisms of n-heptane and isooctane were simplified first by a purely kinetic analysis based on the product formation and then by using a software of simulation of reaction mechanisms.The very different behaviour of these two hydrocarbons was explained by the presence, in the products of isooctane oxidation, of alkenes, which would have an antiknock effect due to the formation of resonance-stabilized radicals. - Keywords: oxidation reaction; n-heptane; isooctane; autoignition; modelling
Simon, Yves,Scacchi, Gerard,Baronnet, Francois
p. 1391 - 1402
(2007/10/03)

Ein molekular definierter, oberflaechengebundener Katalysator zur Olefin-Metathese aus Tris(neopentyl)nitridomolybdaen(VI)
Keywords: Katalyse; Komplexe mit Stickstoffliganden; Molybdaenverbindungen; Polymerisation; ROMP
Herrmann, Wolfgang A.,Stumpf, Andreas W.,Priermeier, Thomas,Bogdanovic, Sandra,Dufaud, Veronique,Basset, Jean-Marie
p. 2978 - 2980
(2007/10/03)

Coke Formation and Its Effects on Shape Selective Adsorptive and Catalytic Properties of Ferrierite
Channels or cavities of ferrierite are blocked by carbonaceous deposits (coke) which are formed during butene treatments.The pore blocking inside ferrierite/alumina catalysts affects the yield and selectivity to isobutylene in the catalytic reaction of butene isomerization.Pore size distribution experiments show that the blocking of 10-member ring channels (4.2 x 5.4 Angstroem) and 8-member ring channels (3.5 x 4.8 Angstroem) of ferrierite by coke reduces the channel size smaller than that of the nitrogen molecule (4.09 Angstroem).TPD data show that ammonia uptake for coked samples of different times on stream is decreased from about 62percent to 35percent of that for the fresh sample.This suggests that channels in coked ferrierites are at least larger than the size of the ammonia molecule (2 Angstroem).Uptakes for more bulky molecules such as 1-butene (2.99 x 4.71 Angstroem) and isobutylene (3.28 x 4.14 Angstroem) are severely reduced by coke formation ( +(XL), H+(L), and H+(S) (XL = extra large, L = large, S = small) from a structural point of view.These three kinds of acid sites were successfully probed with ammonia, 1-butene, and isobutylene.These experiments suggest that the adsorption of probe molecules on ferrierite is also a shape selective process.
Xu, Wen-Qing,Yin, Yuan-Gen,Suib, Steven L.,O'Young, Chi-Lin
p. 758 - 765
(2007/10/02)

Competition of Mechanisms in Nucleophilic Substitution of Vinyl Halides. An Unequivocal Example of the Vinylic SRN1 Route
In a search for an unambiguous example of the vinylic SRN1 route, several vinyl bromides and iodides were reacted mostly with (-)CH2COCMe3, and sometimes with (-)CH2COPh, (-)CH(Me)COEt, and (EtO)2PO(-) ions, under Fe(2+)- or photostimulation in Me2SO.Vinyl halides having vinylic hydrogens, such as β-bromostyrene, gave acetylenic products, e.g., phenylacetylene or a tertiary PhCC-substituted alcohol, whereas vinyl halides with allylic hydrogens, such as Me2C=C(I)CHMe2, gave a substituted allene.Reduction products of the halogen, as well as substitution and rearranged substitution products, were also formed.The operation of ionic elimination-addition routes accounts for formation of most of the products, while the reduction products arise from an intermediate vinyl radical.Ph2C=C(Br)Ph (20) and Me2C=C(Br)Ph (25) gave both substitution and reduction products, but Me2C=C(Br)-t-Bu (23) gave only a reduction product.Formation of substitution products from the conjugated 20 and 25 was ascribed to a reaction via a vinylic SRN1 route, while lack of substitution in 23 is related to its nonconjugated system and to the consequent higher energy that the radical anion of the substitution product would have.The one here reported seems to be the first case of an exclusive genuine vinylic SRN1 process.
Galli, Carlo,Gentili, Patrizia,Rappoport, Zvi
p. 6786 - 6795
(2007/10/02)

The reaction of 1-chloro-2-methyl-2-propenyllithium with a selection of organolithiums. The development and synthetic utility of novel base/nucleophile combinations
The title compound was generated by and reacted with (1) a series of reagents which have basic as well as nucleophilic properties and (2) a series of base/nucleophile combinations.Product yields of the isobutenyl derivative were generally low to very good, and the best results (89percent) were obtained by using a 1:2 ratio (3 equiv total) of nBuLi:LiPPh2.Synthetic utility of the reaction is optimized as it approaches a situation in which the base/nucleophile combination is composed of one compound which is both a strong base and a poor nucleophile and another compound which is both a weak base and a good nucleophile.
Nelson, Donna J.,Nagarajan, Ananthanarayanan
p. 1 - 6
(2007/10/02)

Reaction of Azoalkanes with Isolable Cation Radical Salts
Three tertiary azoalkanes related in the sense acyclic, cyclic, and bicyclic are shown to evolve nitrogen upon oxidation with stable cation radical salts.Thus azo-tert-octane (ATO), 3,3,6,6-tetramethyl-1,2-diazacyclohexene (TMDAC), and 1,4-dimethyl-2,3-diazabicyclooct-2-ene (Me2DBO) react rapidly with thianthrenium perchlorate (Th(.1+)ClO4(1-)), tris(p-bromophenyl)aminium hexachloroantimonate (TBPA(.1+)SbCl6(1-)), and TBPA(.1+)SbF6(1-).The ether and olefin products, which are formed in high yield in CH2Cl2/MeOH solvent, are not those expected from the usual free-radical decomposition of azoalkanes but instead implicate carbocations.Althrough the reaction stoichiometry clearly requires 2 equiv of cation radical salt to one of azoalkane, the mechanism is not yet clearly defined.A complication in these studies is found in the ability of certain cation radical salts to oxidize more azoalkane than expected based on the 2:1 stoichiometry.
Engel, Paul S.,Robertson, Donald M.,Scholz, John N.,Shine, Henry J.
p. 6178 - 6187
(2007/10/02)

Tuning of Tantalum Alkylidene Reactivity with Terdentate Aryl Amine Ligand: Synthesis, Structure and Reactivity of t)>
The terdentate aryldiamine ligand in the aryltantalum(V) alkylidene complex t)> (1) controls alkylidene reactivity in a range of methal-mediated Wittig reactions.An X-ray diffraction study of (1) shows that the hexacoordinate tantalum centre has a very irregular ligand array in which the aryldiamine ligand adopts a new facial N,C,N coordination mode.
Abbenhuis, Hendrikus C. L.,Grove, David M.,Sluis, Paul van der,Spek, Anthony L.,Koten, Gerard van
p. 446 - 448
(2007/10/02)

THERMISCHER ZERFALL VON Β-PHENYL UND Β,Β-DIPHENYL-NITROALKANEN
Elimination of nitrous acid is the exclusive reaction path for the thermal decomposition of the nitroalkanes 1, 2 and 5.Homolytic CC-cleavage cannot compete.A concerted β-elimination is the favoured mechanism.
Fritzsche, Katharina,Beckhaus, Hans-Dieter,Ruechardt, Christoph
p. 2805 - 2808
(2007/10/02)

Electron-transfer processes. 43. Attack of alkyl radicals upon 1-alkenyl and 1-alkynyl derivatives of tin and mercury
Alkyl radicals, obtained by reaction of Bu3Sn? or ClHg? with alkylmercury halides, will undergo regioselective and in some cases stereospecific substitution by a free radical chain addition-elimination mechanism with 1-alkenylstannanes or -mercurials. The chain reaction is also observed for 1-alkynyl derivatives and in the photostimulated demercuration of mixed alkyl and 1-alkenyl- or 1-alkynylmercurials. Chain propagation with alkyl radical formation is also observed to occur in the reactions of β-eliminated ClHg? with Grignard reagents in PhH-THF solution. In competitive reactions of Bu3Sn? or ClHg? with pairs of alkylmercury chlorides, it is observed that a tert-butylmercurial is >1000 times more reactive than a n-butylmercurial, suggesting a concerted dissociate electron-transfer process not involving the intermediacy of RHg? species.
Russell, Glen A.,Ngoviwatchai, Preecha,Tashtoush, Hasan I.
p. 696 - 702
(2008/10/08)

Zur Bildung und Struktur von Isobuten-But-1-en-Codimeren
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Hallpap, Peter,Hartung, Horst,Heublein, Guenther,Schuetz, Heidrun,Stadermann, Dietmar
p. 140 - 142
(2007/10/02)

ACTIVITY OF DIFFERENT STRUCTURAL TYPES OF ZEOLITES IN OLIGOMERIZATION OF C3-C4 OLEFINS
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Minachev, Kh. M.,Bondarenko, T. N.,Kondrat'ev, D. A.
p. 1128 - 1132
(2007/10/02)

A Well-Characterized, Highly Active, Lewis Acid Free Olefin Metathesis Catalyst
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Schaverien, Colin J.,Dewan, John C.,Schrock, Richard R.
p. 2771 - 2773
(2007/10/02)

Synthesis of Alkenes via Peterson Reaction
The α-phenylthiosilanes (2) have been used to prepare the α-silyl anions (1) by reaction with lithium naphthalenide; subsequent condensation with a carbonyl compound gave the alkene (8) via the Peterson reaction.The α-phenylthiosilanes (2) were prepared from n,n-bis(phenylthio)acetals (4) by reaction with lithium naphthalenide and chlorotrimethylsilane.The n,n-bis(phenylthio)acetals (4) were obtained, in turn, from 1,1-bis(phenylthio)acetals (5) by anion formation with butyl-lithium-N,N,N',N'-tetramethylethylenediamine complex in hexane followed by reaction with an alkyl halide.The Peterson reaction was also used to prepare vinyl sulphides (9) and vinyl sulphones (13).
Ager, David J.
p. 183 - 194
(2007/10/02)

Tungsten Wittig Reagents: an Efficient Synthesis of α-Functionalised Tri- and Tetra-substituted Alkenes
The reaction of tungsten alkylidene complexes of the type W(=CR1R2)X2Y2 with organic carbonyl groups is shown to enable a variety of di-, tri-, and tetra-substituted alkenes to be synthesised directly, including enol ethers and enamines.
Aguero, A.,Kress, J.,Osborn, J. A.
p. 531 - 533
(2007/10/02)

THE INFLUENCE OF INTERLAYER WATER ON CLAY CATALYSTS. INTERLAMELLAR CONVERSION OF 2-METHYLPROPENE
Evidence is provided for two alternative pathways for the reactions undergone by 2-methylpropene between the layers of a sheet silicate catalyst (Al3+-exchanged montmorillonite).This clay, when it initially contains ca. 12percent interlayer water, catalyses the addition of either water or methanol to 2-methylpropene to yield, respectively, t-butanol or 2-methoxy-2-methyl propane (methyl tertiary butyl ether, MTBE), whereas the same clay following deliberate dehydration acts as an effective catalyst for the oligomerisation of 2-methylpropene.Similar results are obtained with an Al3+-exchanged synthetic hectorite.
Ballantine, James A.,Jones, William,Purnell, J. Howard,Tennakoon, Dayananda T. B.,Thomas, John M.
p. 763 - 766
(2007/10/02)

Synthesis and Catalytic Properties of W(OAr)2Cl2(CHCMe3)(OR2) and W(OAr)2Cl(CHCMe3)(CH2CMe3)(OR2) (Ar = 2,6-disubstituted phenyl; R = Et or i-Pr), New Uni-component Catalysts for Metathesis of Acyclic and Cyclic Olefins, with or without Functional Groups
The synthesis of W(OAr)2Cl(CHR)(CH2R1)(OR22) (Ar = 2,6-disubstituted phenyl; R2 = Et or i-Pr) illustrates one of the first examples of a well defined, Lewis acid-free, homogeneous olefin metathesis catalyst, for which the activity and stereoselectivity can be governed by the nature of the aryloxide ligands and of the co-ordinated ether and which shows a wide range of potential applications.
Quignard, Francoise,Leconte, Michel,Basset, Jean-Marie
p. 1816 - 1817
(2007/10/02)

OLIGOMERIZATION OF ISOBUTYLENE ON OXIDES COMMUNICATION 3. CATALYTIC PROPERTIES OF ALUMINA-RHENIUM CATALYSTS
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Khodakov, Yu. S.,Anders, K.,Nakhshunov, V. S.,Fel'dgauz, R.,Subbotin, A. N.,et al.
p. 1807 - 1809
(2007/10/02)

Isomerisation of 2,4,4-Trimethylpentenes
The equilibrium in the isomerisation reaction of 2,4,4-trimethylpentenes has been investigated.It is shown on the basis of the experimental heat capacities of the isomers that the ratio of the unreacted di-isobutenes in the temperature range up to 550 deg C does not correspond to equilibrium, while at 550 deg C and above equilibrium is attained.
Muganlinskii, F. F.,Kas'yanov, V. V.,Usenko, M. I.,Kakhramanov, V. B.
p. 851 - 853
(2007/10/02)

Chemistry of the tert-Butyl Radical: Polar Character, ρ Value for Reaction with Toluenes, and the Effect of Radical Polarity on the Ration of Benzylic Hydrogen Abstraction to Addition to Aromatic Rings
We have reexamined the reactions of tert-butyl radicals with toluenes and have obtained a ρ value of 0.49 +/- 0.04 at 80 deg C.The new, independent system involves the quantification of all of the principal products from the reaction of tert-butyl radicals with mixtures of toluene and substituted toluene.Five major products contain benzyl fragments and are formed in significant yields: two symmetrical bibenzyls, the cross bibenzyl, and the two neopentylbenzenes that result from combination of tert-butyl and the two benzyl radicals.Attack on the side chain is a major reaction of free tert-butyl radicals and is the only significant reaction that they undergo other than cage and termination reactions. tert-Butyl radicals do not add to the ring of toluenes.Data on the relative rates of addition to benzenes and hydrogen abstraction from toluenes are collected for a series of radicals including hydrogen atoms; methyl, isopropyl, and tert-butyl radicals; and p-nitrophenyl, p-bromophenyl, and phenyl radicals.The data demonstrate that more electrophilic radicals have a larger tendency to add to rings whereas more nucleophilic radicals have a larger tendency to abstract benzylic hydrogens.
Pryor, William A.,Tang, Felicia Y.,Tang, Robert H.,Church, Daniel F.
p. 2885 - 2891
(2007/10/02)

Pyrolytic Eliminations from N,N-Dichloro Derivatives of Primary, Secondary, and Tertiary Alkyl Primary Amines
N,N-Dichloro derivatives of primary, secondary, and tertiary alkyl primary amines are easily converted to elimination products by neat or solution pyrolysis during GLC at 190-280 deg C.Good to excellent yields result.In general, the type of product formed depends on the alkyl group: with primary alkyl, the products are alkenes and nitriles; with secondary, alkenes and chloroimines result; and with tertiary types, alkenes are formed.Mechanistic aspects are treated.
Roberts, John T.,Rittberg, Barry R.,Kovacic, Peter
p. 4111 - 4115
(2007/10/02)

Mechanism, regiochemistry, and stereochemistry of the insertion reaction of alkynes with methyl(2,4-pentanedionato)(triphenylphosphine)nickel. A cis insertion that leads to trans kinetic products
This study reports the rapid reaction under mild conditions of internal and terminal alkynes with methyl(2,4-pentanedionato)(triphenylphosphine)nickel (1) in aromatic and ethereal solvents. In all cases vinylnickel products (2) are formed by insertion of the alkyne into the nickel-methyl bond. The regiochemistry is unusual; unsymmetrical alkynes give selectively the one regioisomer with the sterically largest substituent next to the nickel atom. So that the stereochemistry of the initial insertion could be investigated, an X-ray diffraction study of the reaction of 1 and diphenylacetylene was carried out. This showed that the vinylnickel complex formed by overall trans insertion was the product of the reaction. Furthermore, subsequent slow isomerization of this complex, to a mixture of it and the corresponding cis isomer, demonstrated that this trans addition product is the kinetic product of the reaction. In studies with other alkynes, the product of trans addition was not always exclusively (or even predominantly) formed, but the ratio of the stereoisomers formed kinetically was substantially different from the thermodynamic ratio. Isotope labeling, added phosphine, and other experiments have allowed us to conclude that the mechanism of this reaction does involve cis addition. However, a coordinatively unsaturated vinylnickel intermediate is initially formed, which can undergo rapid, phosphine-catalyzed cis-trans isomerization in competition with its conversion to the isolable phosphine-substituted products.
Huggins, John M.,Bergman, Robert G.
p. 3002 - 3011
(2007/10/02)

Untersuchungen zur Kinetik und zum Mechanismus der Isooctanoxydation
Isooctan wurde mit Sauerstoff in einem statischen Reaktor aus Rasothermglas im Temperaturbereich zwischen 538 K und 593 K oxydiert.Aus kinetischen Untersuchungen folgt fuer den Bereich der stationaeren Reaktionsgeschwindigkeit ein Zeitgesetz rstat = k32.Die scheinbare Aktivierungsenergie betraegt: EA = 220 +/- 3 kJ/mol.Als charakteristische Reaktionsprodukte wurden 2,2,4,4-Tetramethyltetrahydrofuran, 2-tert.-Butyl-3-methyl-oxetan, α-Diisobuten, β-Diisobuten, β-Diisobutenoxid, Isooktanon sowie 2,2-Dimethylpentanon-3 und -4 gefunden.Aus der Verschiedenartigkeit der Produkte der Isooctanoxydation zu denen der Diisobutenoxydation folgt, dass bei der Alkanoxydation das strukturanaloge Olefin parallel mit anderen sauerstoffhaltigen Produkten gebildet wird.Isootylhydroperoxide koennen unter den Reaktionsprodukten nicht nachgewiesen werden.Durch das Fehlen C-zahlgleicher Hydroperoxide unterscheidet sich iso-Octan hinsichtlich seines Oxydationsverhaltens in charakteristischer Weise von unverzweigten Kohlenwasserstoffen (z.B. n-Heptan).Ein Reactionsmechanismus wird vorgeschlagen.
Lischke, G.,Oehlmann, G.
p. 555 - 572
(2007/10/02)

Thermolabile Hydrocarbons, XIV. Thermal Stability, Strain Enthalpy, and Structure of sym. Hexaalkyl-substituted Ethanes
Activation parameters were determined for the thermolysis reaction of thirteen sym. hexaalkyl-substituted ethanes (Cq-Cq-series).From product analyses it was concluded that the central Cq-Cq-bond is cleaved in the rate determining step by homolysis.A reasonable relationship between the free enthalpy of activation ΔG* (300 deg C) of the reactions and steric substituent constants φfwas observed.Much better correlations were found between ΔG* (300 deg C) and strain enthalpies HS of the hydrocarbons as obtained from molecular mechanics calculations.From the slope of these correlations it is deduced that 40percent residual strain is still present at transition state of these C-C-cleavage reactions.The structural data calculated using Allinger's MM2 force field are distinguished by long central Cq-Cq-bonds (up to 164.1 pm), by large angle deformations on α-C-atoms of side chains and by deviations from the ideal torsional angle Θ = 180 deg along the central bond.The central Cq-Cq-bond length increases in a linear manner with increasing strain enthalpy HS.
Winiker, Robert,Beckhaus, Hans-Dieter,Ruechardt, Christoph
p. 3456 - 3476
(2007/10/02)

Synthesis of ethylenically unsaturated compounds from aldehydes or ketones
Certain hydrocarbylidene-niobium or -tantalum complexes react with aldehydes or ketones to produce ethylenically unsaturated compounds. Exemplary is the reaction of trineopentyl(neopentylidene)tantalum with acetone to produce 2,4,4-trimethyl-2-pentene: EQU1
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(2008/06/13)